1. Field of the Invention
The present invention relates to a plasticizer composition of phthalates of C.sub.9 alcohols. More particularly, it relates to a plasticizer composition of phthalates of C.sub.9 alcohols which give excellent antifreezing property and durability in ageing and other properties as a plasticizer.
2. Description of the Prior Arts
It has been known to use dioctyl phthalate (referring to as DOP) prepared from 2-ethylhexanol as a plasticizer, DOP has excellent characteristics of plasticizing efficient, antifreezing property and electric resistance (volume resistivity), however DOP has inferior durability in ageing (volatile loss).
It has been highly required to obtain a plasticizer having superior property than DOP from the viewpoints of long life of plastics.
It has been known that the durability in ageing (volatile loss) can be improved by using higher alcohols for the preparation of the plasticizer, and olefins for the preparation of phthalates have been studied.
Dinonyl phthalates (referring to as DNP) obtained from C.sub.4 olefins obtained by various processes have significantly improved durability in ageing (volatile loss). However, dinonyl phthalates have not widely used as a plasticizer because either of antifreezing property, electric resistance, plasticizing efficiency or processability is highly inferior.
The known C.sub.8 olefin or C.sub.8 olefin compositions as a starting material for dinonyl phthalates include (1) 2,4,4-trimethylpentene as a dimer of isobutene; (2) C.sub.8 fraction in polymerized gasoline prepared by using a solid phosphoric acid; (3) a dimer of n-butene obtained by using certain organoaluminum compound and nickel compound as a catalyst; and (4) C.sub.8 .alpha.-olefin obtained by polymerization of ethylene.
The components of the known C.sub.8 olefins or C.sub.8 olefin compositions and plasticizing characteristics of the corresponding dinonyl phthalates and dioctyl phthalate (DOP) are shown in Table 1.
All of dinonyl phthalates has superior durability in ageing (volatile loss) to that of DOP.
However, dinonyl phthalates prepared from (1) 2,4,4-trimethylpentene or (2) the C.sub.8 fraction of polymerized gasoline have inferior antifreezing property, plasticizing efficiency and processability whereas dinonyl phthalates prepared from(3) the dimer of n-butene or (4) the C.sub.8 .alpha.-olefin have inferior electric resistance.